The present invention relates to a device for detecting increased pressure in pleural cavity which may be used with a drainage device and more specifically to a device for determining the highest pressure reached during the breathing cycle of a patient over a period of time and comparing the highest pressure reached with prior measurements over a time period.
There have been a number of prior art patents issued on pleural drainage devices utilizing underwater seals to insure that atmospheric air cannot enter the pleural cavity of the patient to which the device is connected. U.S. Pat. Nos. 3,363,626 and 3,363,627 are typical of prior art patent pleural drainage devices which include a collection chamber, underwater seal chamber and manometer chamber. A thoracotomy tube provides a passageway to innerconnect the collection chamber with the pleural cavity of a patient and a passageway is provided on the other side of the underwater seal to connect the drainage device to a source of suction. In operation the water level within the manometer chamber regulates the suction from the suction source to provide the desired degree of vacuum to the collection chamber and the pleural cavity of the patient. Fluids from the pleural cavity collect in the collection chamber and gases from the pleural cavity pass through the underwater seal in the form of bubbles.
Pleural drainage devices such as described above function well in maintaining the desired degree of vacuum in the pleural cavity and the underwater seal provides a means to prevent the entry of atmospheric air into the pleural cavity should, for example, the device become detached from the suction source. It has been found that the underwater seal also performs a further important function. Physicians examining the underwater seal can observe the passage of air bubbles through the seal and by monitoring the frequency of the passage of such bubbles can make a judgment as to the degree of air leak in the pleural cavity of the patient. This use of the underwater seal as a diagnostic tool is important and the present invention enhances this function so that the physician can more accurately determine the condition of the patient even though his time spent with the patient is relatively limited.
The difficulty encountered with prior art drainage devices such as referred to hereinbefore occurs when, for example, no bubbles pass through the underwater seal or only a single bubble passes through the seal during the period of time the physician is with the patient. Under these circumstances, the physician cannot determine the time interval between bubbles nor can he estimate the total volume of air passing out from the pleural cavity of the patient over a given period of time.
In prior application Ser. No. 662,498 referred to hereinbefore, there is disclosed an air leak detector and counter for a drainage device which provides a means for detecting the presence of a bubble passing through the underwater seal of a pleural drainage device and for transmitting a signal to a device which indicates the elapsed period of time between bubbles. Thus, the physician by observing a visual display provided by the device of the time elapsed since a bubble passed through the seal can immediately determine the condition of the patient and make a decision as to when the patient's pleural cavity is healed.